Microrheology of Biopolymer-Membrane Complexes

Helfer, Emmanuèle; Harlepp, Sébastien; Bourdieu, Laurent; Robert, Jérôme; MacKintosh, F. C.; Chatenay, D.

doi:10.1103/physrevlett.85.457

Cited by 126 publications

(118 citation statements)

References 16 publications

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“…In particular, translational invariance implies the proportionality of the divergence of the membrane stress tensor to any applied external forces; if the membrane is closed and the enclosed volume is fixed, this source will be the hydrostatic pressure enforcing the constraint. If the membrane is acted on by a localized external force, as is the case of micro-manipulation techniques [12,13], this will appear as an additional distributional source on the membrane.…”

Section: Introductionmentioning

confidence: 99%

Stresses in lipid membranes

Capovilla

Guven

2002

J. Phys. A: Math. Gen.

169

298

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Abstract. The stresses in a closed lipid membrane described by the Helfrich hamiltonian, quadratic in the extrinsic curvature, are identified using Noether's theorem. Three equations describe the conservation of the stress tensor: the normal projection is identified as the shape equation describing equilibrium configurations; the tangential projections are consistency conditions on the stresses which capture the fluid character of such membranes. The corresponding torque tensor is also identified. The use of the stress tensor as a basis for perturbation theory is discussed. The conservation laws are cast in terms of the forces and torques on closed curves. As an application, the first integral of the shape equation for axially symmetric configurations is derived by examining the forces which are balanced along circles of constant latitude.

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Section: Introductionmentioning

confidence: 99%

Stresses in lipid membranes

Capovilla

Guven

2002

J. Phys. A: Math. Gen.

169

298

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“…Techniques in "active" microrheology, in which a probe colloid is externally forced to move through a material, are currently under investigation using magnetic [20][21][22][23][24][25] or optical forces. 26,27 Active experiments allow the nonlinear response of the material to be tested, and an effective viscosity to be inferred from the relationship between driving force and probe velocity. In such cases, the microstructure itself can be deformed significantly, so that the material response differs from the linear response case, and the fluctuation-dissipation theorem and GSESR relation do not hold.…”

Section: Introductionmentioning

confidence: 99%

A simple paradigm for active and nonlinear microrheology

Squires¹,

Brady²

2005

Physics of Fluids

238

383

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In microrheology, elastic and viscous moduli are obtained from measurements of the fluctuating thermal motion of embedded colloidal probes. In such experiments, the probe motion is passive and reflects the near-equilibrium ͑linear response͒ properties of the surrounding medium. By actively pulling the probe through the material, further information about material properties can be obtained, analogous to large-amplitude measurements in ͑macro-͒ rheology. We consider a simple model of such systems: a colloidal probe pulled through a suspension of neutrally buoyant bath colloids. We choose a system with hard-sphere interactions but neglect hydrodynamic interactions, which is simple enough to permit analytic solutions, but nontrivial enough to raise issues important for the interpretation of experiments in active and nonlinear microrheology. We calculate the microstructural deformation for arbitrary probe size and pulling rate ͑expressed as a dimensionless Péclet number Pe͒. From this, we determine the average retarding effect on the probe due to the microstructure, as well as fluctuations about this average. The high-Pe limit is singular, giving a finite Brownian contribution even in the limit of negligible diffusion. Significantly, different results are obtained for probes driven at constant velocity and constant force. Furthermore, we demonstrate that a probe pulled with an optical tweezer ͑roughly a harmonic well͒ can behave as fixed-force, fixed-velocity, or as a mixture of those modes, depending on the strength of the trap and on the pulling speed. More generally, we discuss how these results relate to previous work on the rheology of colloidal suspensions. Not surprisingly, the present theory ͑which ignores hydrodynamic interactions͒ gives shear thinning but no shear thickening; we expect that the incorporation of hydrodynamics would result in shear thickening as well. The effective micro-and macro-viscosities, when appropriately scaled, are in semi-quantitative agreement. This seems remarkable, given the rather significant difference in the two methods of measurement. However, for more complicated or unknown materials, where such scaling relations may not be known in advance, the comparison between micro-and macro may not be so favorable, which raises important questions about the relation between micro-and macrorheology. Finally, by analogy with previous work on macrorheology, we propose methods to scale up the present ͑dilute͒ theory to account for more concentrated suspensions, and suggest new active microrheological experiments to probe different aspects of suspension behavior.

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“…Examples to date include lipid vesicles below the lipid melting temperature [13], graphite oxide membranes [14], and the red blood cell skeleton [15]. We have recently tailored new microstructures by self-assembly of actin filaments and fluid unilamellar lipid vesicles (ϳ20 mm diameter) [16]. A cross-linked network of actin filaments (mesh size m ϳ 0.1 mm), thick (thickness h ϳ 0.1 mm) compared with a bare lipid membrane, is biochemically bound to the outer leaflet of vesicles [ Fig.…”

mentioning

confidence: 99%

“…1(a)]. These membrane exhibit a viscoelastic behavior at high frequency ͑ f͒: above a few tens of Hz, m and k scale as f z , with z ഠ 0.75 [16]. Mechanical properties of these microstructures are measured using two beads grabbed with optical tweezers and bound to a vesicle via biotin-streptavidin bonds [ Fig The optical tweezers setup is described in Ref.…”

mentioning

confidence: 99%

Buckling of Actin-Coated Membranes under Application of a Local Force

et al. 2001

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Buckling of actin-coated membranes under application of a local forceHelfer, E.; Harlepp, S.; Bourdieu, L.; Robert, J.; MacKintosh, F.C.; Chateney, D. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible.Download date: 11 May 2018 VOLUME 87, NUMBER 8 The mechanical properties of composite membranes obtained by self-assembly of actin filaments with giant fluid vesicles are studied by micromanipulation with optical tweezers. These complexes exhibit typical mechanical features of a solid shell, including a finite in-plane shear elastic modulus ͑ϳ10 26 N͞m͒. A buckling instability is observed when a localized force of the order of 0.5 pN is applied perpendicular to the membrane plane. Although predicted for polymerized vesicles, this is the first evidence of such an instability. P H Y S I C A L R E V I E W L E T T E R S 20 AUGUST 2001 Buckling of Actin-Coated Membranes under Application of a Local Force

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Microrheology of Biopolymer-Membrane Complexes

Cited by 126 publications

References 16 publications

Stresses in lipid membranes

Stresses in lipid membranes

A simple paradigm for active and nonlinear microrheology

Buckling of Actin-Coated Membranes under Application of a Local Force

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